Isolated Drive Assembly With Torque Limiter for FEAD Torque Spikes
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Solution Overview
Problem
Existing front engine accessory drive (FEAD) systems face challenges in attenuating torque spikes transmitted from internal combustion engines, with current solutions being complex, heavy, and prone to failure modes, and elastomeric spring configurations being susceptible to improvement.
Innovation Solution
An isolated drive assembly featuring a drive member, drive member hub, isolator assembly with an elastomeric element, and a torque limiter that uses engageable teeth and grooves to limit torque transmission, preventing excessive rotation and ensuring safe transmission of power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical decoupler with helical compression springs and clutch is used to attenuate torque spikes, then the ability to attenuate torque spikes is improved, but device complexity and weight increase
Solution Approach 1:
The patent extracts the clutch component from the mechanical decoupler system, retaining only the helical compression springs and elastomeric spring elements. This eliminates the complex clutching mechanism while preserving torque spike attenuation capability through the elastic deformation of the spring elements alone.
Solution Approach 2:
The patent replaces the mechanical clutch system with an elastomeric spring-based isolation mechanism. The elastomeric element provides passive torque attenuation through its viscoelastic properties, eliminating the need for active clutch engagement and disengagement mechanisms.
2Reliability
If a mechanical decoupler with clutch is used to attenuate torque spikes, then the ability to attenuate torque spikes is improved, but weight increases
Solution Approach 1:
The patent removes the heavy clutch components from the mechanical decoupler, retaining only the lightweight spring elements. The elastomeric spring provides sufficient torque attenuation with significantly reduced mass compared to a full mechanical decoupler with clutch.
Solution Approach 2:
The patent changes the material parameters by using elastomeric materials with high damping capacity and viscoelastic properties. This allows achieving the same torque attenuation function with lighter material density and reduced component mass.
3Reliability
If elastomeric spring is used to rotationally couple pulley and hub, then torque spike attenuation is achieved, but the system becomes susceptible to improvement
Solution Approach 1:
The patent employs composite construction by combining metal helical compression springs with elastomeric spring elements in a hybrid isolator assembly. This composite approach leverages the high strength and elastic recovery of metal springs with the damping and shock absorption capabilities of elastomers, creating a more robust and improvement-resistant system.
Solution Approach 2:
The patent introduces dynamic adjustment capabilities through the isolator assembly design, allowing the elastomeric element's operational characteristics to be optimized. The isolator assembly enables controlled engagement and disengagement of the elastomeric spring, providing dynamic response to varying torque conditions and reducing susceptibility to performance degradation.
4Reliability
If torque limiter with engageable teeth and grooves is added to limit torque transmission, then protection against excessive rotation is improved, but device complexity increases
Solution Approach 1:
The patent merges the torque limiter functionality directly into the isolator assembly structure. The engageable teeth and grooves are integrated with the existing isolator components rather than being separate additions, thereby providing torque transmission protection while minimizing overall device complexity.
Solution Approach 2:
The isolator assembly is designed to perform multiple functions simultaneously: torque spike attenuation through the elastomeric spring, mechanical coupling between drive member and hub, and torque limitation through engageable teeth and grooves. This multi-functionality reduces the need for separate dedicated components for each function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The isolated drive assembly effectively attenuates torque spikes, providing a reliable and efficient means of power transmission while minimizing the risk of failure, by using a silicone rubber element and torque limiter to manage rotational direction and magnitude, thus enhancing the stability and safety of FEAD systems.
Implementation Method 1
The elastomeric element resiliently couples the isolator hub and the isolator rim
Implementation Method 2
The torque limiter is configured to limit the transmission of torque through a resilient element of the isolator assembly
Data Source
AI summary
An isolated drive assembly that includes a drive member, which is rotatable about a rotational axis, a drive member hub, which is rotatable about the rotational axis relative to the drive member, an isolator assembly, which has an elastomeric element that transmits rotary power between the drive member and the drive member hub, and a torque limiter. The torque limiter has first and second sets of engagable limiter elements that limit rotation of the drive member relative to the drive member hub in opposite rotational directions to limit a magnitude of a moment that is transmitted through the elastomeric element.